Lead alloy



Patented Aug. 21, 1928.

UNITED STATES PATENT OFFICE.

HIROSHI YOSHIKAWA, OF TOKYO, J'AJPAN.

LEAD ALLOY.

No Drawing. Application filed November 12, 1926, Serial No. 148,104, and in Japan November 30, 1925.

This invention relates to alloys of lead containing a small quantity of'a metal which is immiscible with lead, such as copper, nickel, cobalt, manganese, chromium or aluminium, and has for its object ,to provide an alloy having leadas a base, but having better physical properties.

This invention also comprises a lead alloy containing, besides one of the said immiscible metals, a small quantity of bismuth.

Lead excels all the other metals of daily use in its resisting power against chemical corroding actions, but the practical merit thereof is very much decreased owing to its interior physical properties. According to my invention, not only the superior chemical properties have been enhanced, but the physical properties thereof, especially those relating to hardness and tensile strength, were greatly improved, enabling lead to be vmost advantageously' used for covering galvanized wires and plates, for covering telephone and telegraph cables, and also for the? manufacture of the pipes for conveying water and other chemical liquids.

According to myexperimcnts, the physical properties of lead can greatly be improved by adding to it a small quantity of a metal immiscible with lead, such as copper, nickel, cobalt, manganese. chromium or aluminium. Hardness and especially tensile strength of lead can be increased considerably, without appreciable loss in maleability, by the addition of a small quantity, below 10 per cent, of one or several of the metals above mentioned.

If a small quantity of bismuth is added to the lead alloy just mentioned, the same forming a solid solution of one phase with lead up to about 10 per cent content, it will bestow very beneficial. effects on the alloy in the way of reducing the coetficient of friction and of increasing mobility in molten state, thereby facilitating casting of the same or shaping to any desired form. As to the coeflicient of friction, I found that it decreases with the percentage content of bismuth and attains a minimum at 0.25 per cent.

In the following are given some of the results of experiments conducted by me with regard to a test piece of a bar six inches long, the central portion of which consisted ot a circular rod of length 2 inches and diameter 12 mm.

Lead- Copper- [Bismuth- Tensile content contentcoutent strength Elonga- (per (per (per (kgs. tions cent) cent) cent) per cm 99. 9 o. 1 204 9i. 3 99. 0. 1 0. 25 214 93. 4 93. l 1.0 0. 25 214 91. 6

given in percentage, that of pure lead 'quently it will require less power at the pump ng station, as compared with ordinary lead pipe. If used for the covering of telephone cables, a considerable saving in the covering material may be effected. due to its increased strength. Or more precisely, its tensile strength being nearly twice that of pure lead, the cross sectional area of the lead covering may be reduced by one half an amount.

In my invention. the percentage content of a metal immiscible with lead may widely vary according to the circumstances. However, it will not very much exceed one per cent and in any event it will not exceed 10 per cent.

\Vhat I claim is:

1 An alloy consisting of lead, bismuth and a metal immiscible with lead of the group: copper and nickel, wherein the bismuth content lies between 0.025% and 01. 1; and the content of the metal immiscible with the lead lies between 0.025% and 5.0%.

2. An alloy consisting of lead, bismuth and at least one of the metals immiscible with lead and of the group copper, nickel, cobalt, manganese, chromium and aluminium, wherein the bismuth content lies between 0.025% and 4.0% and the content of the metal immiscible with lead lies between 0.025% and 5.0%.

3. An allo consisting of lead, bismuth and a pluraity of the metals immiscible with lead and of the group: copper, nickel, cobalt, manganese, chromium and aluminium, wherein the bismuth content lies between 0.025% and 4.0% and the aggregate 1 content of the metals immiscible with lead lies between 0.025% and 5.0%.

4. An alloy consisting of lead, bismuth and copper, wherein the content of bismuth lies between 0.025% and 4.0% and that of 15 copper between 0.025% and 5.0%.

In testimony whereof, I afiix my signature,

HIROSHI YOSHIKAWA. 

